Small (< 10-mm) incidentally found intracranial aneurysms, Part 1: reasons for detection, demographics, location, and risk factors in 212 consecutive patients

Neurosurg Focus. 2011 Dec;31(6):E3. doi: 10.3171/2011.9.FOCUS11234.


Object: The widespread use of imaging techniques for evaluating nonspecific symptoms (vertigo, dizziness, memory concerns, unsteadiness, and the like) and focal neurological symptoms related to cerebrovascular disease has led to increased identification of asymptomatic incidentally discovered unruptured intracranial aneurysms (UIAs). The management of these incidental aneurysms is controversial and many factors need to be considered. The authors describe reasons leading to diagnosis, demographics, and risk factors in a large consecutive series of patients with small incidentally found UIAs.

Methods: The authors prospectively evaluated 335 patients harboring 478 small (< 10-mm) UIAs between January 2008 and May 2011. Patients with known aneurysms, possibly symptomatic aneurysms, arteriovenous malformation-related aneurysms, patients with a history of subarachnoid hemorrhage from another aneurysm, and patients harboring extradural aneurysms were excluded from the analysis. Only truly incidental small aneurysms (272 aneurysms in 212 patients) were considered for the present analysis. Data regarding the reason for detection, demographics, location, and presence of potential risk factors for aneurysm formation were prospectively collected.

Results: There were 158 female (74.5%) and 54 male (25.5%) patients whose mean age was 60.6 years (median 62 years). The most common reason for undergoing the imaging study that led to a diagnosis of the aneurysms was evaluation for nonspecific spells and symptoms related to focal cerebrovascular ischemia (43.4%), known/possible intracranial or neck pathology (24%), and headache (16%). The most common location (27%) of the aneurysm was the middle cerebral artery; the second most common (22%) was the paraclinoid internal carotid artery (excluding cavernous sinus aneurysms). Sixty-nine percent of patients were current or prior smokers, 60% had a diagnosis of hypertension, and 23% had one or more relatives with a history of intracranial aneurysms with or without subarachnoid hemorrhage.

Conclusions: Small incidental UIAs are more commonly diagnosed in elderly individuals during imaging performed to investigate ill-defined spells or focal cerebrovascular ischemic symptoms, or during the evaluation of known or probable unrelated intracranial/neck pathology. Hypertension, smoking, and family history of aneurysms are common in this patient population, and the presence of these risk factors has important implications for treatment recommendations. Although paraclinoid aneurysms (excluding intracavernous aneurysms) are uncommon in patients with ruptured intracranial aneurysms, this location is very common in patients with small incidental UIAs.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Female
  • Humans
  • Incidental Findings*
  • Intracranial Aneurysm / diagnosis*
  • Intracranial Aneurysm / epidemiology*
  • Male
  • Middle Aged
  • Prospective Studies
  • Risk Factors